U.S. patent application number 14/009489 was filed with the patent office on 2014-01-30 for method and apparatus for performing ranging at m2m device in a wireless communication system.
This patent application is currently assigned to LG ELECTRONICS INC.. The applicant listed for this patent is Hangyu Cho, Jinsoo Choi, Jinsam Kwak, Kiseon Ryu. Invention is credited to Hangyu Cho, Jinsoo Choi, Jinsam Kwak, Kiseon Ryu.
Application Number | 20140029539 14/009489 |
Document ID | / |
Family ID | 47009796 |
Filed Date | 2014-01-30 |
United States Patent
Application |
20140029539 |
Kind Code |
A1 |
Choi; Jinsoo ; et
al. |
January 30, 2014 |
METHOD AND APPARATUS FOR PERFORMING RANGING AT M2M DEVICE IN A
WIRELESS COMMUNICATION SYSTEM
Abstract
A method and apparatus for performing ranging at a Machine to
Machine (M2M) device in a wireless communication system are
disclosed. The method includes receiving a Primary SuperFrame
Header (P-SFH) and a Secondary SuperFrame Header (S-SFH), receiving
an Advanced Air Interface-System Configuration Descriptor (AAI-SCD)
message, and performing dedicated ranging using M2M dedicated
ranging information included in the AAI-SCD message, wherein first
count information included in the S-SFH is increased whenever the
M2M dedicated ranging information are changed, wherein information
indicating a change in the S-SFH, included in the P-SFH are not
changed by update of the first count information.
Inventors: |
Choi; Jinsoo; (Anyang-si,
KR) ; Cho; Hangyu; (Anyang-si, KR) ; Kwak;
Jinsam; (Anyang-si, KR) ; Ryu; Kiseon;
(Anyang-si, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Choi; Jinsoo
Cho; Hangyu
Kwak; Jinsam
Ryu; Kiseon |
Anyang-si
Anyang-si
Anyang-si
Anyang-si |
|
KR
KR
KR
KR |
|
|
Assignee: |
LG ELECTRONICS INC.
Seoul
KR
|
Family ID: |
47009796 |
Appl. No.: |
14/009489 |
Filed: |
March 29, 2012 |
PCT Filed: |
March 29, 2012 |
PCT NO: |
PCT/KR2012/002321 |
371 Date: |
October 2, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61474729 |
Apr 12, 2011 |
|
|
|
61504709 |
Jul 6, 2011 |
|
|
|
Current U.S.
Class: |
370/329 |
Current CPC
Class: |
H04W 48/12 20130101;
H04L 27/2602 20130101; H04L 5/0096 20130101 |
Class at
Publication: |
370/329 |
International
Class: |
H04L 5/00 20060101
H04L005/00 |
Claims
1. A method for performing ranging at a Machine to Machine (M2M)
device in a wireless communication system, the method comprising:
receiving a Primary SuperFrame Header (P-SFH) and a Secondary
SuperFrame Header (S-SFH); receiving an Advanced Air
Interface-System Configuration Descriptor (AAI-SCD) message; and
performing dedicated ranging using M2M dedicated ranging
information included in the AAI-SCD message, wherein first count
information included in the S-SFH is increased whenever the M2M
dedicated ranging information are changed, wherein information
indicating a change in the S-SFH, included in the P-SFH are not
changed by update of the first count information.
2. The method according to claim 1, wherein the AAI-SCD message
includes second count information that increases whenever the M2M
dedicated ranging information is changed, and the first count
information indicates the second count information.
3. The method according to claim 1, wherein the S-SFH including the
first count information is an S-SFH SubPacket 3 Information Element
(S-SFH SP3 IE).
4. The method according to claim 3, wherein the M2M device always
decodes the S-SFH SP3 IE even though the P-SFH does not indicate
the S-SFH SP3 IE.
5. The method according to claim 1, wherein the information
indicating a change in the S-SFH, included in the P-SFH comprise an
S-SFH change count and an S-SFH SP change bitmap.
6. The method according to claim 1, wherein the M2M dedicated
ranging information includes information about M2M dedicated
ranging resources.
7. The method according to claim 1, wherein a configuration change
count included in the AAI-SCD message is not increased even though
the dedicated ranging information is changed.
8. A method for transmitting ranging information at a Base Station
(BS) in a wireless communication system, the method comprising:
transmitting a Primary SuperFrame Header (P-SFH) and a Secondary
SuperFrame Header (S-SFH); and transmitting an Advanced Air
Interface-System Configuration Descriptor (AAI-SCD) message,
wherein first count information included in the S-SFH is increased
whenever the M2M dedicated ranging information are changed, wherein
information indicating a change in the S-SFH, included in the P-SFH
are not changed by update of the first count information.
9. The method according to claim 8, wherein the AAI-SCD message
includes second count information that increases whenever the M2M
dedicated ranging information is changed, and the first count
information indicates the second count information.
10. The method according to claim 8, wherein the S-SFH including
the first count information is an S-SFH SubPacket 3 Information
Element (S-SFH SP3 IE) and the M2M device always decodes the S-SFH
SP3 IE even though the P-SFH does not indicate the S-SFH SP3
IE.
11. The method according to claim 8, wherein the information
indicating a change in the S-SFH, included in the P-SFH comprise an
S-SFH change count and an S-SFH SP change bitmap.
12. The method according to claim 8, wherein the M2M dedicated
ranging information includes information about M2M dedicated
ranging resources.
13. The method according to claim 8, wherein a configuration change
count included in the AAI-SCD message is not increased even though
the dedicated ranging information is changed.
14. A Machine to Machine (M2M) device for performing ranging in a
wireless communication system, comprising: a Radio Frequency (RF)
unit; and a processor, wherein the processor receives a Primary
SuperFrame Header (P-SFH), a Secondary SuperFrame Header (S-SFH),
and an Advanced Air Interface-System Configuration Descriptor
(AAI-SCD) message through the RF unit and controls dedicated
ranging to be performed using M2M dedicated ranging information
included in the AAI-SCD message, and wherein first count
information included in the S-SFH is increased whenever the M2M
dedicated ranging information are changed, wherein information
indicating a change in the S-SFH, included in the P-SFH are not
changed by update of the first count information.
15. A Base Station (BS) for transmitting ranging information in a
wireless communication system, comprising: a Radio Frequency (RF)
unit; and a processor, wherein the processor transmits a Primary
SuperFrame Header (P-SFH), a Secondary SuperFrame Header (S-SFH),
and an Advanced Air Interface-System Configuration Descriptor
(AAI-SCD) message through the RF unit, and wherein first count
information included in the S-SFH is increased whenever the M2M
dedicated ranging information are changed, wherein information
indicating a change in the S-SFH, included in the P-SFH are not
changed by update of the first count information.
Description
TECHNICAL FIELD
[0001] The present invention relates to wireless communications,
and more particularly, to a method for performing network reentry
at a Machine to Machine (M2M) device and the M2M device in a
wireless communication system.
BACKGROUND ART
[0002] Legacy communication is mostly Human to Human (H2H)
communications conducted via a Base Station (BS). Now, the
development of communication technology enables M2M communication.
As its appellation implies, M2M communication is communications
between electronic terminals. While M2M communications means wired
or wireless communication between electronic terminals or
communication between a human-controlled terminal and a machine in
its broadest sense, it is typical in these days that M2M
communication refers to wireless communication between electronic
terminals, i.e. terminals.
[0003] When the concept of M2M communication was introduced in the
early 1990s, it was regarded merely as the concept of remote
control or telematics and its market was very limited. However, M2M
communication has been drastically developed and the M2M
communication market has attracted much attention all over the
world including Korea over the past few years. Especially, M2M
communication has a great influence on the fields of fleet
management, remote monitoring of machines and facilities, smart
metering for automatically measuring the working time of
construction equipment and the consumption of heat or electricity,
etc. in the market of Point Of Sales (POS) and security-related
applications. It is expected that M2M communication will find its
various uses in conjunction with legacy mobile communication, very
high-speed wireless Internet or Wireless Fidelity (WiFi), and
low-output communication solutions such as Zigbee and thus will
extend to Business to Customer (B2C) markets beyond Business to
Business (B2B) markets.
[0004] In the era of M2M communication, every machine equipped with
a Subscriber Identity Module (SIM) card can be managed and
controlled remotely because it is possible to transmit data to and
receive data from the machine. For example, M2M communication is
applicable to a very broad range including numerous terminals and
equipment such as a car, a truck, a train, a container, an
automatic vending machine, a gas tank, etc.
[0005] As the application types of M2M devices have been increasing
in number, a number of such M2M devices may exist in the same BS.
When a huge number of M2M devices in idle state attempt network
reentry, connection collisions and congestions increase, thus
degrading communication performance. However, there is no specified
procedure for performing network reentry in idle state by an M2M
device having different characteristics from an existing terminal
(H2H terminal).
DISCLOSURE OF INVENTION
Technical Problem
[0006] An object of the present invention devised to solve the
problem lies on a method and apparatus for performing a network
reentry procedure, which can efficiently support an M2M device,
while minimizing an influence on a network reentry procedure of an
existing terminal, that is, a Human to Human (H2H) terminal in a
wireless communication system.
[0007] It will be appreciated by persons skilled in the art that
the objects that could be achieved with the present invention are
not limited to what has been particularly described hereinabove and
the above and other objects that the present invention could
achieve will be more clearly understood from the following detailed
description taken in conjunction with the accompanying
drawings.
Solution to Problem
[0008] The object of the present invention can be achieved by
providing a method for performing ranging at a Machine to Machine
(M2M) device in a wireless communication system, including
receiving a Primary SuperFrame Header (P-SFH) and a Secondary
SuperFrame Header (S-SFH), receiving an Advanced Air
Interface-System Configuration Descriptor (AAI-SCD) message, and
performing dedicated ranging using M2M dedicated ranging
information included in the AAI-SCD message, wherein first count
information included in the S-SFH is increased whenever the M2M
dedicated ranging information are changed, wherein information
indicating a change in the S-SFH, included in the P-SFH are not
changed by update of the first count information.
[0009] In another aspect of the present invention, provided herein
is a method for transmitting ranging information at a Base Station
(BS) in a wireless communication system, including transmitting a
P-SFH and an S-SFH, and transmitting an AAI-SCD message, wherein
first count information included in the S-SFH is increased whenever
the M2M dedicated ranging information are changed, wherein
information indicating a change in the S-SFH, included in the P-SFH
are not changed by update of the first count information.
[0010] In another aspect of the present invention, provided herein
is an M2M device for performing ranging in a wireless communication
system, including a Radio Frequency (RF) unit and a processor. The
processor receives a P-SFH, an S-SFH, and an AAI-SCD message
through the RF unit and controls dedicated ranging to be performed
using M2M dedicated ranging information included in the AAI-SCD
message, wherein first count information included in the S-SFH is
increased whenever the M2M dedicated ranging information are
changed, wherein information indicating a change in the S-SFH,
included in the P-SFH are not changed by update of the first count
information.
[0011] In a further aspect of the present invention, provided
herein is a BS for transmitting ranging information in a wireless
communication system, including an RF unit and a processor. The
processor transmits a P-SFH, an S-SFH, and an AAI-SCD message
through the RF unit, wherein first count information included in
the S-SFH is increased whenever the M2M dedicated ranging
information are changed, wherein information indicating a change in
the S-SFH, included in the P-SFH are not changed by update of the
first count information.
[0012] According to the above aspects, the AAI-SCD message may
include second count information that increases whenever the M2M
dedicated ranging information is changed, and the first count
information may indicate the second count information.
[0013] The S-SFH including the first count information may be an
S-SFH SubPacket 3 Information Element (S-SFH SP3 IE).
[0014] The M2M device may always decode the S-SFH SP3 IE even
though the P-SFH does not indicate the S-SFH SP3 IE.
[0015] The information indicating a change in the S-SFH, included
in the P-SFH may be an S-SFH change count and an S-SFH SP change
bitmap.
[0016] The M2M dedicated ranging information may include
information about M2M dedicated ranging resources.
[0017] A configuration change count included in the AAI-SCD message
may not be increased even though the dedicated ranging information
is changed.
Advantageous Effects of Invention
[0018] According to the embodiments of the present invention, an
M2M device can perform network reentry fast and efficiently, while
minimizing an influence on an existing terminal (H2H terminal) in a
wireless communication system.
[0019] It will be appreciated by persons skilled in the art that
that the effects that could be achieved with the present invention
are not limited to what has been particularly described hereinabove
and other advantages of the present invention will be more clearly
understood from the following detailed description taken in
conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0020] The accompanying drawings, which are included to provide a
further understanding of the invention, illustrate embodiments of
the invention and together with the description serve to explain
the principle of the invention.
[0021] In the drawings:
[0022] FIG. 1 illustrates the structure of a superframe in an
Institute of Electrical and Electronics Engineers (IEEE) 802.16m
system as an exemplary wireless communication system;
[0023] FIG. 2 illustrates update of Secondary SuperFrame Header
(SFH) Information Elements (IEs) in the IEEE 802.16m system;
[0024] FIG. 3 is a diagram illustrating states of a User Equipment
(UE) in the IEEE 802.16m system;
[0025] FIG. 4 is a diagram illustrating a signal flow for
performing contention-based network reentry at a UE in the IEEE
802.16m system;
[0026] FIG. 5 is a diagram illustrating a signal flow for
performing non-contention-based network reentry at a UE in the IEEE
802.16m system;
[0027] FIG. 6 is a diagram illustrating a signal flow for
performing non-contention-based network reentry at a Machine to
Machine (M2M) device according to an embodiment of the present
invention;
[0028] FIG. 7 is a diagram illustrating a signal flow for
performing non-contention-based network reentry at an M2M device
according to an embodiment of the present invention;
[0029] FIG. 8 illustrates a relationship among an Advanced Air
Interface-System Configuration Descriptor (AAI-SCD) message, a
Primary SFH (P-SFH) IE, and an S-SFH IE;
[0030] FIG. 9 illustrates a relationship among an AAI-SCD message,
a P-SFH IE, and an S-SFH IE according to an embodiment of the
present invention; and
[0031] FIG. 10 is a block diagram of an M2M device and a Base
Station (BS) according to an embodiment of the present
invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0032] Reference will now be made in detail to the preferred
embodiments of the present invention with reference to the
accompanying drawings. The detailed description, which will be
given below with reference to the accompanying drawings, is
intended to explain exemplary embodiments of the present invention,
rather than to show the only embodiments that can be implemented
according to the invention. The following detailed description
includes specific details in order to provide a thorough
understanding of the present invention. However, it will be
apparent to those skilled in the art that the present invention may
be practiced without such specific details. For example, the
following detailed description is given under the assumption that a
system conforming to Institute of Electrical and Electronics
Engineers (IEEE) 802.16 is being used. However, the description is
applicable to any other wireless communication system (e.g. Long
Term Evolution (LTE)/LTE-Advanced (LTE-A) except for specific
features inherent to the IEEE 802.16 standards.
[0033] In some instances, known structures and devices are omitted
or are shown in block diagram form, focusing on important features
of the structures and devices, so as not to obscure the concept of
the invention. The same reference numbers will be used throughout
this specification to refer to the same or like parts.
[0034] In the following description, the term terminal generically
refers to a mobile or fixed user terminal device such as a User
Equipment (UE), a Mobile Station (MS), or an Advanced Mobile
Station (AMS). In addition, the term Base Station (BS) generically
refers to any node at a network end which communicates with a UE,
such as a Node B, an evolved Node B (eNode B), an Access Point
(AP), an Advanced BS (ABS), etc. The following description is given
on the assumption that a UE is a AMS conforming to the IEEE 802.16m
standard and a BS is also an ABS conforming to the IEEE 802.16m
standard.
[0035] In a wireless communication system, a UE can receive
information from a BS on a downlink and transmit data to the BS on
an uplink. Information transmitted from or received at the UE
includes data and various types of control information. There are
many physical channels depending on the types and usages of
information transmitted from or received at UEs.
[0036] A terminal that conducts Machine to Machine (M2M)
communication may be referred to as various names such as an M2M
device, an M2M communication terminal, and a Machine Type
Communication (MTC) terminal. Existing terminals may be referred to
as Human Type Communication (HTC) terminals or Human to Human (HTH)
terminals.
[0037] As the number of machine application types increases, M2M
devices will also be gradually increased in number. Machine
application types under consideration are (1) security; (2) public
safety; (3) tracking and tracing; (4) payment; (5) healthcare; (6)
remote maintenance and control; (7) metering; (8) consumer devices;
(9) fleet management in Point Of Sales (POS)-related and
security-related application markets; (10) communication between
terminals at a vending machine; (11) remote control of machines and
facilities and smart metering for automatically measuring the
operation time of construction machines and facilities and heat or
power consumption; and (12) surveillance video communication, which
should not be construed as limiting the present invention. Besides,
many other machine application types are being discussed. As
machine application types get diversified in this manner, the
number of M2M devices is increasing, compared to the number of
existing terminals, that is, H2H terminals.
[0038] The existence of numerous M2M devices within the service
area of the same BS may cause connection congestions between the
M2M devices and the existing terminals, i.e. H2H terminals and
connection collisions between the M2M devices. Accordingly, there
exists a need for discussing how efficiently to distribute limited
resources to a newly emerged huge number of M2M devices, while
minimizing their effects on the existing terminals (H2H
terminals).
[0039] That is, if a network reentry procedure for idle-mode
existing terminals (i.e. H2H terminals) is still applied to a
plurality of M2M devices, connection congestions may occur between
existing H2H terminals and M2M devices in view of the nature of the
M2M devices. Therefore, the network reentry procedure needs to be
partially modified.
[0040] FIG. 1 illustrates the structure of a superframe in an IEEE
802.16m system as an exemplary wireless communication system.
[0041] Referring to FIG. 1, a superframe is 20 ms long, including
four frames. Each frame is further divided into eight subframes. In
Time Division Duplexing (TDD), eight subframes may be divided into
a Downlink (DL) subframe area and an Uplink (UL) subframe area and
the DL and UL subframe areas include predetermined numbers of
subframes according to a DL/UL ratio. Referring to FIG. 1(b), if
the UL/DL ratio is 5:3, five out of eight subframes are allocated
as DL subframes SF0 to SF4 and the remaining three subframes are
allocated as UL subframes SF5, SF6 and SF7.
[0042] An idle time to which no data symbol carrying data (i.e. no
effective symbol) is allocated, called Transmit/receive Transition
Gap (TTG) is interposed between the DL subframe area and the UL
subframe area. An idle time called Receive/transmit Transition Gap
(RTG) may also exist after the DL subframe area. One subframe
includes six Orthogonal Frequency Division Multiplexing (OFDM)
symbols.
[0043] A BS and a UE may exchange data with each other using the
above-described frame structure. For example, the UE may receive
data from the BS in DL subframes and may transmit data to the BS in
UL subframes. The BS may transmit data to the UE in the DL
subframes and may receive data from the UE in the UL subframes.
[0044] In the above-described frame structure, a SuperFrame Header
(SFH) may be transmitted to the UE in a superframe. The SFH may
deliver system information or resource allocation information about
each frame or subframe included in the superframe. The SFH may
reside in the first subframe of the superframe, occupying five OFDM
symbols.
[0045] The SFH may be divided into a Primary Superframe Header
(P-SFH) and a Secondary Superframe Header (S-SFH).
[0046] The P-SFH may be transmitted in every superframe, carrying
system information for the superframe. The P-SFH may contain an
S-SFH change count field, S-SFH scheduling information field, an
S-SFH change bitmap field, and an S-SFH application hold indicator
field.
[0047] The S-SFH change count field may indicate whether the value
of each field in S-SFH SP IEs has been changed (updated). That is,
if the value of any field in the S-SFH SP IEs has been changed, the
S-SFH change count field is incremented by 1 modulo 16, beginning
with the next S-SFH change cycle. The changed S-SFH change count
field is maintained until the second next S-SFH change cycle. If
the value of an S-SFH change count field in the next P-SFH IE is
equal to a value stored in the UE, the UE neglects the S-SFH IEs,
determining that the S-SFH IEs remain unchanged.
[0048] The S-SFH change bitmap field may indicate a changed S-SFH
SubPacket (SP) IE. The bits of the S-SFH change bitmap field
represent an S-SFH SP1 IE, an S-SFH SP2 IE, and an S-SFH SP3 IE,
respectively. When an S-SFH SP IE is changed, the bit corresponding
to the S-SFH SP IE may be set to 1 and otherwise, the bit may be
set to 0. For example, if the S-SFH SP3 IE is changed, the S-SFH SP
change bitmap field may be expressed as 100.
[0049] The S-SFH application hold indicator field may explicitly
indicate a time at which a changed SFH SP IE is to be applied. If
the S-SFH application hold indicator field is 0, the UE uses an
S-SFH SP IE associated with the current S-SFH change count field.
If the S-SFH application hold indicator field is 1, the UE uses an
S-SFH SP IE associated with a previous S-SFH change count
field.
[0050] The S-SFH may carry network entry/reentry information and
may be divided into three SPs each having a different periodicity.
Information about these periodicities may be included as SP
scheduling periodicity information in the S-SFH SP3 IE. The S-SFH
SP1 IE includes network reentry information, the S-SFH SP2 IE
includes information for initial network entry and network
discovery, and the S-SFH SP3 IE includes the other required system
information for network entry/reentry.
[0051] FIG. 2 is a view referred to for describing update of the
S-SFH IEs in the IEEE 802.16m system, especially when information
included in the S-SFH SP3 IE is changed.
[0052] Referring to FIG. 2, an S-SFH change cycle of 32 is given
and a specific S-SFH SP IE is transmitted every SuperFrame Number
(SFN). For example, if a BS changes network reentry information in
the S-SFH SP3 IE of SFN 10, a CC representing an S-SFH change count
field is incremented by 1, beginning with the start of the next
S-SFH change cycle, SFN 32. Additionally, a CB representing an
S-SFH change bitmap field is changed from 000 to 100 in order to
indicate that the changed S-SFH IE is the S-SFH SP3 IE.
[0053] Upon receipt of a P-SFH IE, a UE checks the S-SFH change
count field and recognizes that the CC is larger than K stored in
the UE by 1 in SFN 32, which means that an S-SFH SP IE has been
changed. Then the UE identifies from the CB that the S-SFH SP3 IE
has been changed and awaits reception of the S-SFH SP3 IE. The UE
receives the first changed S-SFH SP3 IE in SFN 35 and decodes it so
as to use changed network reentry information, beginning with SFN
36. If the changed S-SFH IE is the S-SFH SP1 IE or S-SFH SP2 IE,
the changed contents are applied beginning with the second
transmitted changed S-SFH IE.
[0054] In this manner, the UE may determine which S-SFH SP IE to
decode in the current superframe to update system parameters
broadcast within the S-SFH SP IEs based on the S-SFH change count
field, the S-SFH SP change bitmap field, and the S-SFH application
hold indicator field.
[0055] Meanwhile, an Advanced Air Interface-System Configuration
Descriptor (AAI-SCD) message is used for a BS to transmit system
configuration information periodically. When the contents of the
AAI-SCD message are changed, the value of a Configuration Change
Count field is incremented by 1 modulo 16.
[0056] The BS indicates when a changed AAI-SCD message will be
applied through an SCD count field of the S-SFH SP3 IE. After
transmitting an S-SFH SP3 IE including an SCD count field equal to
the configuration change count of the AAI-SCD message, the BS
applies the changed system configuration.
[0057] Meanwhile, the UE receives system configuration information
in an AAI-SCD message associated with the current SCD count field.
If the AAI-SCD change is caused by update of the S-SFH SP 3 IE, the
new AAI-SCD message is transmitted before the changed S-SFH SP3.
After receiving the changed S-SFH SP3, the UE may use a system
configuration indicated by the AAI-SCD message associated with the
current SCD count field.
[0058] FIG. 3 is a diagram illustrating states of a UE in the IEEE
802.16m system.
[0059] Referring to FIG. 3, UE states may be divided largely into a
connected state and an unconnected state. The connected state may
further be divided into normal mode and sleep mode. The unconnected
state may further be divided into idle mode and Deregistration with
Context Retention (DCR) mode. Both the sleep mode and the idle mode
are defined to efficiently use the power consumption of UEs.
[0060] In the sleep mode, a sleep mode pattern is used for power
saving. The sleep mode pattern is composed of a sleep window and a
listening window, approved by a BS through exchange AAI Sleep
Request and AAI Sleep Response (AAI-SLP-REQ/AAI-SLP-RSP) messages
between the BS and a UE. The idle mode uses a paging group, a
paging cycle, and a paging offset that are approved by the BS
through exchange of AAI Deregistration Request (AAI-DREG-REQ) and
AAI Deregistration Command (AAI-DREG-CMD) messages between the BS
and the UE.
[0061] The normal mode is a mode in which a UE implements a
system-provided service using radio resources. In the DCR mode, the
UE is deregistered from a network but its context is preserved for
a predetermined time.
[0062] A basic sleep-mode operation will be described below. When
UL or DL traffic has not been generated in the normal mode for a
predetermined time, the UE transmits an AAI-SLP-REQ message to the
BS to request transition to the sleep mode. Upon receipt of the
sleep-mode operation request in the AAI-SLP-REQ message, the BS
finally accepts the request of the AAI-SLP-RSP message and the UE
operates in the sleep mode, after it is allocated an Identifier
(ID) (SLPID) identifying a sleep-mode UE through an AAI-SLP-RSP
message.
[0063] Important parameters acquired through message transmission
and reception between the UE and the BS are an initial sleep window
indicating an initial sleep window size, a final sleep window base
indicating a last sleep window size, a final sleep-window exponent,
a listening window indicating a listening window size. These
parameters are all represented in frames. The sleep window refers
to a period in which a sleep-mode UE minimizes its power. Thus the
UE does not receive DL control information and DL traffic during
the sleep window. The listening window is a period in which the
sleep-mode UE transitions from the sleep window, receives an AAI
Traffic Indication (AAI-TRF-IND) message from the BS, and
determines the presence or absence of DL traffic directed to it.
The UE may receive DL control information and DL traffic during the
listening window.
[0064] Now a description will be given of a basic idle-mode
operation. When no UL or DL traffic has been generated in the
normal mode, the UE transmits an AAI-DREG-REQ message to the BS to
request transition to the idle mode. Then the UE receives an
AAI-DREG-CMD message from the BS and operates in the idle mode. The
AAI-DREG-REQ message defines a UE-requested paging cycle. Upon
receipt of the AAI-DREG-REQ message, the BS defines a paging group
ID, a paging offset, and a paging cycle in the AAI-DREG-CMD
message. The UE sets a paging unavailable interval and a paging
listening interval based on the parameters.
[0065] The UE minimizes its power during the paging unavailable
interval and receives an AAI Paging Advertisement (AAI-PAG-ADV)
message from the BS during the paging listening interval. The
AAI-PAG-ADV message includes the paging group ID of a paging group
to which the BS belongs, Medium Access Control (MAC) address hash
information indicating UEs requiring location update or network
entry/reentry among idle-mode UEs, and an action code that
describes a procedure that each UE should perform.
[0066] Upon generation of traffic directed to an idle-mode UE, the
BS transmits an AAI-PAG-ADV message to the UE during the next
paging listening interval. Upon receipt of the AAI-PAG-ADV message,
the UE transitions from the idle mode to the normal mode.
[0067] A process of adjusting transmission parameters (a frequency
offset, a time offset, and transmission power) for UL communication
with the BS by the UE during network entry or network reentry in
the idle mode is called ranging.
[0068] There are four ranging modes: initial ranging, handover
ranging, periodic ranging, and bandwidth request ranging.
[0069] Initial ranging is a process of adjusting transmission
parameters (a frequency offset, a time offset, and transmission
power) for UL communication with a BS by a UE during initial
network entry. Handover ranging is a simplified ranging process for
handover of a UE. Periodic ranging is a process of maintaining UL
communication with a BS by a UE after network entry. Bandwidth
request ranging is performed for a UE to request a UL bandwidth to
a BS, upon generation of UL traffic.
[0070] In the wireless communication system, the network allocates
a ranging code (or a ranging preamble) and a ranging code
transmission area (i.e. a Ranging Channel (RCH)) for ranging on a
channel that broadcasts system information (e.g., a Broadcast
Assignment A-MAP IE) according to the type of ranging. For example,
to perform handover ranging, a UE selects a specific ranging code
from among available ranging codes and requests ranging by
transmitting the selected ranging code to the network on a handover
RCH. The network may identify the ranging type from the ranging
code and the channel carrying the ranging code.
[0071] In the IEEE 802.16m system, RCHs are classified into a
Synchronized Ranging Channel (S-RCH) for ranging of a synchronized
UE and a Non-Synchronized Ranging Channel (NS-RCH) of ranging of a
non-synchronized UE. A Bandwidth Request Channel (BRCH) is also
defined for a UE to request a UL bandwidth upon generation of data
to be transmitted. These RCHs (the S-RCH and the NS-RCH) and the
BRCH are used as a ranging opportunity and a bandwidth request
opportunity, respectively at the MAC layer.
[0072] A transmission scheme of ranging code and RCH allocation
information and an allocated RCH are determined according to a BS
type.
[0073] For example, in case of a BS supporting a WirelessMAN-OFDMA
with FDM-based UL PUSC Zone and a BS having narrow coverage such as
a femtocell, asynchronization between a UE and a BS is less likely.
Therefore, an S-RCH is used for any of initial ranging, handover
ranging, and periodic ranging.
[0074] Ranging code and RCH allocation information is basically
transmitted in an SFH (SP1: a Ranging Parameter (RP), code
partition information for the S-RCH, an allocation periodicity of
the S-RCH, and a subframe offset of the S-RCH).
[0075] In case of the other BSs (e.g. a macro BS, a relay, and a
macro hot-zone), an NS-RCH is used during initial ranging or
handover ranging. When a UE is already synchronized, the UE uses an
S-RCH during periodic ranging.
[0076] Ranging code and RCH allocation information is basically
transmitted in an SFH (SP1: an RP, code partition information for
the NS-RCH, an allocation periodicity of the NS-RCH, and a subframe
offset of the NS-RCH). Besides the SFH, RCH allocation information
may be transmitted in an A-MAP or AAI-SCD message. In case of an
A-MAP, NS-RCH allocation information for handover ranging may be
transmitted in a Broadcast Assignment A-MAP IE or an AAI-HO-CMD
message in a subframe other than a subframe used for allocation of
broadcast data according to a scheduling determination of a BS. If
an AAI-SCD message is used, it includes information about an S-RCH
allocation period and the number of ranging codes for periodic
ranging.
[0077] FIG. 4 is a diagram illustrating a signal flow for
performing contention-based network reentry at a UE in the IEEE
802.16m system.
[0078] Referring to FIG. 4, a UE selects an RCH and a
contention-based ranging code and transmits the contention-based
ranging code on the selected RCH (S110). Upon successful receipt of
the ranging code, a BS broadcasts an AAI Ranging ACKnowledgment
(AAI-RNG-ACK) message to the UE (S120). The AAI-RNG-ACK message is
a response message indicating that ranging codes have been
successfully received on RCHs. The BS masks a Code Division
Multiple Access (CDMA) allocation A-MAP IE being UL resource
allocation information for transmission of an AAI-RNG-REQ message
from the UE by a Random Access Identifier (RA-ID) and transmits the
masked CDMA allocation A-MAP IE to the UE (S130). The UE transmits
an AAI-RNG-REQ message to the BS in allocated UL resources (S140),
and the BS transmits DL resource allocation information for
transmission of an AAI-RNG-RSP message to the UE (S150). Herein,
the DL resource allocation information may be transmitted to the UE
in a CDMA allocation A-MAP IE or Broadcast DL basic assignment
A-MAP IE masked by the RA-ID. Then the UE may receive an
AAI-RNG-RSP message in allocated DL resources (S160).
[0079] FIG. 5 is a diagram illustrating a signal flow for
performing non-contention-based network reentry at a UE in the IEEE
802.16m system. Non-contention-based handover ranging is taken as
an example.
[0080] Referring to FIG. 5, a serving BS transmits a dedicated
ranging code in an AAI Handover Command (AAI-HO-CMD) message to a
UE (S210). The UE transmits the allocated dedicated ranging code to
a target BS (S220). The target BS notifies the UE of successful
reception of the dedicated ranging code by unicasting a Station
Identifier (STID)-based AAI Ranging ACKnowledgment (AAI-RNG-ACK)
message (S230). Upon receipt of the dedicated ranging code, the
target BS identifies the UE that has transmitted the dedicated
ranging code. The AAI-HO-CMD message includes an STID allocated to
the UE in advance by the target BS as well as the dedicated ranging
code. In this case, because the UE has already acquired the STID,
the AAI-RNG-ACK message may not be transmitted in an RA-ID-based
manner. The target BS transmits UL resource allocation information
for transmission of an AAI-RNG-REQ message from the UE by
unicasting an STID-based UL basic assignment A-MAP IE (S240). The
UE transmits an AAI-RNG-REQ message to the target BS in allocated
UL resources (S250), and the BS transmits DL resource allocation
information for transmission of an AAI-RNG-RSP message to the UE by
an STID-based DL basic assignment A-MAP IE (S260). Then, the UE may
receive the AAI-RNG-RSP message in allocated DL resources
(S270).
[0081] As described before, a BS transmits a dedicated ranging code
and an STID preliminarily allocated to a UE in an AAI-HO-CDM
message during non-contention-based ranging for network reentry.
However, an M2M device performs a ranging procedure based on an
RA-ID during non-contention-based ranging for network reentry,
discrimination from other existing RA-ID-based ranging procedures
becomes an issue.
[0082] First of all, an RA-ID will be described briefly. The RA-ID
is 15 bits in total, defined according to the random access
characteristic of a UE. Specifically, the RA-ID includes a 5-bit
SFN, a 2-bit frame index, a 6-bit preamble code index for ranging,
and a 2-bit opportunity index for ranging. The 6-bit preamble code
index indicates a ranging code, and the 2-bit opportunity index
indicates an RCH carrying the ranging code. Specifically, the
opportunity index is set to `0b00` indicating NS-RCH, to `0b11`
indicating S-RCH, and to `0b01/0b10` indicating dynamic RCH. That
is, the 6-bit ranging code and the 2-bit information indicating an
RCH carrying the ranging code are main elements of the RA-ID.
[0083] FIG. 6 is a diagram illustrating a signal flow for
performing non-contention-based network reentry at an M2M device
according to an embodiment of the present invention.
[0084] Referring to FIG. 6, a BS may set one dedicated ID (e.g. one
dedicated STID). The STID may be used for an M2M device or M2M
devices during non-contention-based network reentry. The BS
broadcasts an AAI-PAG-ADV message including the dedicated STID
(S310).
[0085] The BS transmits information about an RA-ID list/set in a
specific IE masked by the dedicated STID to the M2M device or M2M
devices (S320). The RA-ID list/set information may include
information about dedicated ranging codes and RCHs. The specific IE
may be a UL basic allocation A-MAP IE or a broadcast A-MAP IE.
Alternatively, the RA-ID list/set information may be transmitted in
a newly defined IE. A method for masking a CRC by a dedicated STID
will be described below in detail with reference to Table 1, Table
2, and Table 3.
[0086] An M2M device selects an RCH and a ranging code and
transmits the ranging code on the selected RCH to the BS (S330).
The BS masks the CRC of a CDMA allocation A-MAP IE being UL
resource allocation information for transmission of an AAI-RNG-REQ
message from the M2M device by an RA-ID and transmits the
CRC-masked CDMA allocation A-MAP IE to the M2M device (S340). The
M2M device transmits an AAI-RNG-REQ message to the BS in allocated
UL resources (S350), and the BS transmits DL resource allocation
information for transmission of an AAI-RNG-RSP message to the M2M
device (S360). Then, the M2M device may receive the AAI-RNG-RSP
message from the BS in allocated DL resources (S370).
[0087] If corresponding M2M devices form a specific paging group,
one dedicated STID may be transmitted in a field related to a
paging group ID in the AAI-PAG-ADV message. If the M2M devices are
included in a single M2M group, an M2M Group Identifier (MGID) may
be used instead of one dedicated STID.
[0088] Table 1, Table 2 and Table 3 illustrate CRC masks in the
IEEE 802.16m system. A CRC is composed of a 1-bit masking prefix, a
3-bit type indicator, and the other 12 bits.
TABLE-US-00001 TABLE 1 Masking Prefix Remaining 15 bit LSBs (1 bit
MSB) Type Indicator Masking Code 0b0 0b000 12 bit STID or TSTID
0b001 Refer to Table 844 0b010 Refer to Table 845 0b1 15 bit RA-ID:
The RA-ID is derived from the AMS random access attributes (i.e..
superframe number (LSB 5 bits). frame_index (2 bits). preamble code
index for ranging or BR (6 bits) and opportunity index for ranging
or BR (2 bits)) as defined below: RA-ID = (LSB 5 bits of superframe
number frame_index preamble_code_index opportunity_index)
[0089] Referring to Table 1, Masking Prefix is 1 bit set to `0b0`
or `0b1`. If Masking Prefix is `0b0`, this implies a masking code
according to a type indicator. Only type indicators of `0b000`,
`0b001`, and `0b010` are defined. If the type indicator is `0b000`,
this indicates a 12-bit STID or TSTID. If the type indicator is
`0b001`, Table 844 is referred to. If the type indicator is
`0b010`, Table 845 is referred to. Table 844 and Table 845
correspond to Table 2 and Table 3, respectively.
[0090] Table 2
TABLE-US-00002 TABLE 2 Table 844 - Description of the Masking Code
for type indicator 001 Decimal Value Description 0 Used to mask
Broadcast Assignment A-MAP IE for broadcast or ranging channel
assignment 1 Used to mask BR-ACK A-MAP IE 2-128 Used to mask Group
Resource Allocation A-MAP IE (group ID) Others Reserved
TABLE-US-00003 TABLE 3 Table 845 - Description of the Masking Code
for type indicator 010 Decimal Value Description 4095 Used to mask
Broadcast Assignment A-MAP IE for multicast assignment Others
Reserved
[0091] In a CRC masking method using a dedicated STID according to
the present invention, a conventionally defined STID is still used,
which includes a masking prefix set to `0b0`, a type indicator set
to `0b000`, and a 12-bit masking code. A Broadcast Assignment A-MAP
IE for allocating M2M dedicated ranging resources may be CRC-masked
by a value with a masking prefix set to `0b0`, a type indicator set
to `0b001`, and a decimal value of `129` or `4095`. Or, a Broadcast
Assignment A-MAP IE for allocating M2M dedicated ranging resources
may be CRC-masked by a value with a masking prefix set to `0b0`, a
type indicator set to `0b010`, and a decimal value of `0` or
`4094`. Meanwhile, a Function Index set to `0b11` may be defined as
an index for M2M dedicated ranging resource allocation in the
Broadcast Assignment A-MAP IE and this field may include RA-ID
list/set information. In addition, when an MGID is used instead of
a single dedicated STID, the above-described CRC masking method may
also be performed in the same manner.
[0092] FIG. 7 is a diagram illustrating a signal flow for
performing non-contention-based network reentry at an M2M device
according to an embodiment of the present invention.
[0093] Referring to FIG. 7, a BS may allocate M2M dedicated ranging
resources including an M2M dedicated ranging code and an RCH (or a
ranging opportunity) (S410). In this case, an M2M device may
perform non-contention-based network reentry using the dedicated
ranging resources.
[0094] The BS transmits information about the allocated M2M
dedicated ranging resources to the M2M device (S420). Methods for
transmitting the information about the allocated M2M dedicated
ranging resources will be described later in detail. If the BS does
not allocate M2M dedicated ranging resources, the M2M device may
perform a network reentry procedure in ranging resources indicated
by an S-SFH SP1 IE. Subsequently, the M2M device performs ranging
for network reentry in the allocated dedicated ranging resources.
That is, the M2M device transmits the allocated dedicated ranging
code on the allocated RCH to the BS (S430). The BS masks a CDMA
Allocation A-MAP IE being UL resource allocation information for
transmission of an AAI-RNG-REQ message from the M2M device by an
RA-ID and transmits the masked CDMA Allocation A-MAP IE to the M2M
device (S440).
[0095] The opportunity index of the RA-ID by which the CDMA
Allocation A-MAP IE is masked may be set to one of `0b01` and
`0b10`, to serve a different purpose and usage different from a
conventional purpose and usage. The set opportunity index may be
used as a type indicator indicating an M2M dedicated ranging code
or RCH. In this case, the opportunity index indicating a dynamic
RCH (e.g. a dynamic NS-RCH) should be set to any other value. For
instance, if an opportunity index is set to `0b01` to indicate an
M2M dedicated ranging code or RCH, the opportunity index should be
set to `0b10` to indicate a dynamic RCH.
[0096] The M2M device may transmit an AAI-RNG-REQ message to the BS
in allocated UL resources (S450). The M2M device may receive DL
resource allocation information for DL transmission of an
AAI-RNG-RSP message from the BS (S460) and receive the AAI-RNG-RSP
message in allocated DL resources (S470).
[0097] A description will be given of how to indicate allocated M2M
dedicated ranging resources to an M2M device or M2M devices. If
information about allocated dedicated ranging resources is
transmitted in an AAI-HO-CMD message as is done to an H2H terminal,
the allocation information should be unicast to a plurality of
individual M2M devices, thereby increasing overhead. In this
context, a method for broadcasting information about allocated
dedicated ranging resources in an S-SFH, an AAI-SCD message, or a
Broadcast Assignment A-MAP IE is proposed. When the S-SFH is used,
there is no space available in the S-SFH SP1 IE and S-SFH SP2 IE
due to existing information in them. Although the S-SFH SP3 IE has
space to additionally transmit the information about allocated
dedicated ranging resources, collision between M2M devices and H2H
terminals should be considered because the S-SFH SP3 IE carries
system configuration information for all UEs. Accordingly, a
careful approach is required to transmit the information about
allocated dedicated ranging resources on the S-SFH.
[0098] One of methods for transmitting information about allocated
M2M dedicated ranging resources is to use an AAI-SCD message.
Preferably, the information about allocated M2M dedicated ranging
resources is transmitted in the AAI-SCD message, and related
control information is transmitted on the S-SFH.
[0099] A dedicated ranging region and a dedicated ranging code
index/set may be additionally defined in the AAI-SCD message. The
dedicated ranging region indicates an M2M dedicated RCH and the
dedicated ranging code index indicates an M2M dedicated ranging
code.
[0100] If one subband is already used as the dedicated ranging
region for M2M in the frequency domain, one more subband may be
allocated. The position of the additional subband may be indicated
by the resource index of the subband following a cell-specific
ranging subband or the resource index of a subband spaced by a
specific offset. The offset is preset or indicated by the
S-SFH.
[0101] In addition, the index of a subframe of the M2M dedicated
RCH may be indicated from the temporal and spatial perspectives. In
this case, if up to one subframe per frame and even dynamic ranging
are considered, allocation of an additional subframe in an
environment supporting up to two subframes per frame is not viable
in a frame structure having two UL subframes. Thus dedicated
ranging resource allocation may be prohibited in the frame
structure having two UL subframes. For example, the validity of a
subframe index may be determined by an operation for indicating
dedicated ranging allocation.
[0102] The dedicated ranging code index/set is 5 bits, for
representing up to 32 M2M dedicated ranging codes. In addition, the
dedicated ranging code index/set may be configured separately for
each M2M device by adding an MGID to this field.
[0103] Meanwhile, if dedicated ranging resource allocation
information is updated by transmitting a dedicated ranging change
count field for the dedicated ranging resource allocation
information in both the S-SFH and the AAI-SCD message, unnecessary
information decoding oft H2H terminals and non-associated M2M
devices may be prevented, as described later with reference to FIG.
9.
[0104] Another method for transmitting M2M dedicated ranging
resource allocation information is to use a Broadcast Assignment
A-MAP IE. The Broadcast Assignment A-MAP IE includes Number of
Ranging Opportunities, Subframe index, and Ranging opportunity
index. Information about a dedicated RCH and a dedicated ranging
code may be provided using these fields.
[0105] Meanwhile, the Broadcast Assignment A-MAP IE includes the
Function Index field. The Function Index field indicates what
information is carried in the Broadcast assignment A-MAP IE.
Specifically, if the Function Index is `0b00`, this implies that
the Broadcast Assignment A-MAP IE delivers broadcast assignment
information. If the Function Index field is `0b01`, this implies
that the Broadcast Assignment A-MAP IE delivers handover ranging
channel allocation information. If the Function Index field is
`0b10`, this implies that the Broadcast Assignment A-MAP IE
delivers multicast assignment information. `0b11` is reserved.
Herein, if the Function Index is `0b01`, a dynamic RCH for handover
is indicated by two ranging opportunity indexes. Therefore, one of
the ranging opportunity indexes may be used to indicate M2M
dedicated ranging resource allocation.
[0106] Alternatively, the reserved value of the Function Index,
`0b11` may be defined to indicate M2M dedicated ranging resource
allocation. Thus, when the Function Index is set to `0b11`, M2M
dedicated ranging resource allocation information may be
transmitted in the field (e.g., a subframe index, an RCH index, and
a ranging code index).
[0107] A third method for transmitting M2M dedicated ranging
resource allocation information is to define an M2M dedicated
Broadcast Assignment A-MAP IE that only M2M devices can receive and
decode. For this purpose, the M2M dedicated Broadcast Assignment
A-MAP IE may be CRC-masked by an MGID or an M2M dedicated STID and
transmitted so as to prevent H2H terminals and non-related M2M
devices from decoding the M2M dedicated Broadcast Assignment A-MAP
IE.
[0108] However, decoding the M2M dedicated Broadcast A-MAP IE all
the time may impose a constraint on M2M devices requiring low-power
consumption. Therefore, only when the M2M dedicated ranging
indicator field indicates M2M dedicated ranging in the S-SFH SP3
IE, the M2M devices may decode the M2M dedicated Broadcast
Assignment A-MAP IE. In this case, the M2M dedicated Broadcast
Assignment A-MAP IE is transmitted at a predetermined position
(e.g. a predetermined frame and subframe) or in the S-SFH SP3
IE.
[0109] Hereinbelow, a description will be given of methods for,
when an AAI-SCD message includes M2M dedicated ranging resource
allocation information, preventing existing HTC terminals from
decoding the information unnecessarily.
[0110] Before describing the methods, a relationship among an
AAI-SCD message, a P-SFH IE, and an S-SFH IE will be described with
reference to FIG. 8. In FIG. 8, the AAI-SCD message, the P-SFH IE,
and the S-SFH SP3 IE are illustrated and fields that are not
related to the following description of each format are not
provided herein. The configuration change count field of the
AAI-SCD message indicates whether the AAI-SCD message has been
changed.
[0111] If system information carried in the AAI-SCD message has
been changed, the configuration change count field of the AAI-SCD
message is incremented and thus the SCD count field of the S-SFH
SP3 IE indicating the configuration change count field is also
changed (incremented) (801). To indicate that the S-SFH SP3 IE has
been changed, an S-SFH IE change count field and an S-SFH SP change
bitmap field are set in the P-SFH IE (803). Therefore, after
decoding the P-SFH IE and then decoding an S-SFH SP3 IE indicated
by the S-SFH SP change bitmap field, the UE may be aware from the
SCD count field that system information has been changed in the
AAI-SCD message. Subsequently, the UE may receive a new AAI-SCD
message including the changed system information and apply the
changed system information.
[0112] Meanwhile, if information included in the S-SFH SP3 IE has
been changed, the SCD count field of the S-SFH SP3 IE is changed.
To indicate the change of the S-SFH SP3 IE, the S-SFH IE change
count field and the S-SFH SP change bitmap field are set in the
P-SFH IE (802). The change of the SCD count field leads to the
change of the configuration change count field of the AAI-SCD
message (803). This AAI-SCD message is transmitted to the UE before
the changed S-SFH SP3 IE is transmitted. The UE may acquire changed
information in the S-SFH SP3 IE by decoding the P-SFH IE.
[0113] In the case where the AAI-SCD message includes M2M dedicated
ranging information, when the M2M dedicated ranging information is
changed, the configuration change count field of the AAI-SCD
message and then the SCD count field of the S-SFH SP3 IE are
changed, as described above. In addition, the S-SFH IE change count
field and S-SFH SP change bitmap fields of the P-SFH IE are
changed. In this case, all UEs that have received the AAI-SCD
message necessarily decode an S-SFH SP3 IE indicated by the decoded
P-SFH IE in a superframe. As a consequence, existing HTC terminals
that do not need the M2M dedicated ranging information
unnecessarily decode the information. Accordingly, the present
invention provides methods for allowing only M2M devices requiring
M2M dedicated ranging information to decode the M2M dedicated
ranging information.
[0114] One of the methods for allowing only M2M devices requiring
M2M dedicated ranging information to decode the M2M dedicated
ranging information is to transmit a field indicating a change in
the M2M dedicated ranging information in both the AAI-SCD message
and the S-SFH SP3 IE. Referring to FIG. 9, the AAI-SCD message may
include second count information (i.e. an M2M configuration change
count field) indicating a change in the M2M dedicated ranging
information, and the S-SFH SP3 IE may include first count
information for M2M (i.e. an M2M SCD count field) interacting with
the M2M configuration change count field (i.e. indicating the M2M
configuration change count field). If the M2M dedicated ranging
information is changed in the AAI-SCD message, the M2M
configuration change count field of the AAI-SCD message is changed
and thus the M2M SCD count field of the S-SFH SP3 IE is also
changed (901).
[0115] Unlike the SCD count field, the change of the M2M SCD count
field may not cause a change in information included in the P-SFH
IE (the S-SFH change count field and the S-SFH SP change bitmap
field) (902). In other words, even though the M2M dedicated ranging
information is changed in the AAI-SCD message, the information of
the P-SFH IE is not reconfigured. Since the S-SFH IE change count
field and S-SFH change bitmap field do not indicate a change of an
S-SFH SP3 IE in the P-SFH IE, existing HTC terminals not related to
the M2M dedicated ranging information may not decode the S-SFH SP3
IE. However, M2M devices may not know the change of the M2M SCD
count field of the S-SFH SP3 IE simply by decoding the P-SFH IE.
Therefore, the M2M devices may be configured so as to decode the
S-SFH SP3 IE all the time.
[0116] Even though the M2M dedicated ranging information is
additionally changed, the configuration change count field of the
AAI-SCD message may not be changed. If the configuration change
count field of the AAI-SCD message is changed in this case, even
though the change of the M2M SCD count field does not cause a
change in the information of the P-SFH (the S-SFH change count
field and the S-SFH SP change bitmap field), the configuration
change count field is incremented due to the changed M2M dedicated
ranging information of the AAI-SCD message. Successively, the SCD
count field of the S-SFH SP3 IE is changed. To indicate the change
of the SCD count field, information of the P-SFH IE is changed. HTC
terminals always decode the P-SFH. Since the information of the
P-SFH IE indicates the change of the S-SFH SP3, the HTC terminals
decode unnecessary M2M dedicated ranging information.
[0117] According to the above description, operations of an HTC
terminal and an M2M device will be summarized as follows.
[0118] For the HTC terminal, i) dedicated ranging information may
be changed or ii) any other information may be changed. In the case
of i), the HTC terminal receives a superframe, decodes a P-SFH IE,
and determines that the S-SFH IE change count field and S-SFH
change bitmap field of the P-SFH IE have not been changed (because
the changed dedicated ranging information does not affect
information included in the P-SFH IE). Therefore, the HTC terminal
does not decode an S-SFH IE.
[0119] In the case of ii), the HTC terminal receives a superframe,
decodes a P-SFH IE, and determines an S-SFH IE to be decoded from
the S-SFH IE change count field and S-SFH change bitmap field of
the P-SFH IE (for example, if the S-SFH change bitmap field=100,
the HTC terminal decodes the S-SFH SP3 IE). Subsequently, the HTC
terminal acquires changed information by decoding the S-SFH IE.
[0120] Similarly for the M2M device, iii) dedicated ranging
information may be changed or iv) any other information may be
changed. In the case of iii), the M2M device receives a superframe,
decodes a P-SFH IE, and determines that no S-SFH IEs have been
changed (because the changed dedicated ranging information dos not
affect information included in the P-SFH IE). However, the M2M
device is supposed to always decode the S-SFH SP3 IE as described
before and thus decodes the S-SFH SP3 IE. The M2M device may
determine that the M2M SCD count field of the S-SFH SP3 IE has been
changed and thus acquire dedicated ranging information from a
later-received AAI-SCD message.
[0121] In the case of iv), the M2M device operates in the same
manner as the HTC terminal in the case of ii) except that the M2M
device decodes the S-SFH SP3 IE even though the S-SFH IE change
count field and S-SFH change bitmap field of the P-SFH IE indicates
that an S-SFH IE other than the S-SFH SP3 IE has been changed.
[0122] Meanwhile, an information field indicating a time and/or
periodicity for indicating dedicated ranging information may be
included in the S-SFH SP3 IE so that an M2M device may decode the
S-SFH SP3 IE according to the periodicity.
[0123] Secondly, the M2M SCD count field may be transmitted in a
paging message (e.g. an AAI-PAG-ADV message) and the M2M
configuration change count field may be transmitted in an AAI-SCD
message. In this case, an M2M device or M2M group that performs
network entry/network reentry using the paging message may be aware
from the M2M SCD count field and the M2M configuration change count
field that dedicated ranging information carried in the AAI-SCD
message has been updated and even a time of applying the updated
dedicated ranging information.
[0124] The M2M device may store a previous count and determine when
the updated information will be transmitted by comparing the stored
count with a new received count. Information about the applying
time may be acquired in the same manner as in a conventional
AAI-SCD update procedure.
[0125] Thirdly, a new message may be defined to transmit the M2M
SCD count field. Advantageously, even the initial network entry of
an M2M device may be supported. Because a UE may not know a
transmission time and transmission periodicity of the new message,
the new message needs to be transmitted at a specific time with a
specific periodicity. Therefore, the transmission time of the new
message may be set to a superframe corresponding to an S-SFH change
cycle known to all UEs. For example, a message carrying the M2M SCD
count field may be transmitted in the first superframe of the S-SFH
change cycle, and the S-SFH change cycle may be set as the
transmission cycle of the new message. The subsequent operation is
performed in the same manner as in the first method.
[0126] The foregoing methods may be applied according to a
later-described ranging indicator, for example, on the condition
that the ranging setting indicator indicates M2M dedicated
ranging.
[0127] Now a description will be given of an indicator indicating
whether an M2M device will perform contention-based network entry
or non-contention-based network entry. A large amount of
contention-based ranging resources may need to be allocated to H2H
terminals according to the environment of the wireless
communication system. In this case, a relatively large amount of
non-contention-based ranging resources may need to be allocated to
M2M devices. On the contrary, there may be a case where a large
amount of non-contention-based ranging resources are to be
allocated to H2H terminals and a relatively large amount of
contention-based ranging resources are to be allocated to M2M
devices.
[0128] An M2M ranging indicator field may be defined to indicate
one of the above cases according to an environment, thereby
enabling efficient use of limited resources. Basically, it is
assumed that M2M dedicated ranging resource information is
transmitted in an AAI-SCD message, which should not be construed as
limiting the present invention.
[0129] The M2M ranging indicator field may be configured so as to
indicate contention-based ranging for M2M devices (i.e., the same
normal ranging as for HTC terminals), non-contention-based ranging
(i.e. dedicated ranging for M2M devices), network reentry not
allowed for M2M devices, and/or both non-contention-based ranging
and contention-based ranging available to M2M devices. To indicate
the contents, the M2M ranging indicator field may be 1 bit or 2
bits.
[0130] When the M2M ranging indicator field is 1 bit, it may be set
to `0b0` to indicate non-contention-based ranging and to `0b1` to
indicate only contention-based ranging. The value of the M2M
ranging indicator field, `0b0` may mean that non-contention-based
ranging is allowed, in other words, both non-contention-based
ranging and contention-based ranging are available. It may be
further contemplated that an M2M shared ranging allowance indicator
is additionally defined to indicate that only non-contention-based
ranging is allowed. Then the M2M shared ranging allowance indicator
may be set to `0b0` to indicate that contention-based ranging is
allowed and to `0b1` to indicate that only non-contention-based
ranging is allowed.
[0131] On the other hand, the M2M ranging indicator field may be
configured such that `0b0` indicates contention-based ranging and
`0b1` indicates only non-contention-based ranging. The value `0b0`
means that contention-based ranging is allowed, that is, both
contention-based ranging and non-contention-based ranging are
available. An M2M dedicated ranging allowance indicator may be
additionally defined such that `0b0` indicates that
non-contention-based ranging is allowed and to `0b1` indicates that
only contention-based ranging is allowed.
[0132] The M2M ranging indicator field may be 2 bits in the
following cases. If it is `0b00`, the M2M ranging indicator field
may indicate normal ranging without allowing dedicated ranging for
M2M devices. If it is `0b01`, the M2M ranging indicator field may
indicate dedicated ranging for M2M devices, and if it is `0b10`,
the M2M ranging indicator field may indicate that both
contention-based ranging and non-contention-based ranging are
available to M2M devices. If it is `0b11`, the M2M ranging
indicator field may indicate that network entry/reentry is not
allowed for M2M devices. Mapping between values and their meanings
may be changed and all or a part of the four values may be
used.
[0133] As described above, the M2M ranging indicator field may be
included in a message/format defined in the IEEE 802.16m system.
That is, the M2M ranging indicator field may be included in an
AAI-SCD message, an S-SFH SP IE, or a Broadcast Assignment A-MAP
IE.
[0134] In the case where the M2M ranging indicator field is
included in an AAI-SCD message, it may be understood that inclusion
of the M2M ranging indicator field in an S-SFH IE is a load. As
described before, the M2M ranging indicator field of the AAI-SCD
message may be 1 or 2 bits. Unlike the above description of a 2-bit
M2M ranging indicator field, the M2M ranging indicator field may be
configured so as to indicate normal ranging without allowing
dedicated ranging for M2M devices, if it is `0b00`, dedicated
ranging for M2M devices, if it is `0b01`, and network entry/reentry
not allowed for M2M devices, if it is `0b10`.
[0135] Or, the 5-bit dedicated ranging code index/set included in
the AAI-SCD message may be defined to additionally indicate whether
only contention-based ranging or only non-contention-based ranging
is allowed.
[0136] In the case where the M2M ranging indicator field is
included in an S-SFH SP IE, the M2M ranging indicator field may
also be 1 or 2 bits, which will not be described in detail herein
to avoid redundancy.
[0137] In the case where the M2M ranging indicator field is
included in a Broadcast Assignment A-MAP IE for M2M devices of a
specific M2M group, the M2M ranging indicator field may also be 1
or 2 bits. An ID identifying the M2M group (e.g. an MGID) may be
added. Or, ranging may be set for a specific M2M device or M2M
group by including the M2M ranging indicator field in a paging
message for the specific M2M device or M2M group that performs
network reentry in idle mode.
[0138] The M2M ranging indicator field may be used in an IEEE
802.16e system. In this case, a method for preventing the use of
the M2M ranging indicator field from affecting legacy UEs is
needed. To be more specific, UL-MAP IEs each having a fixed length
for a plurality of UEs are transmitted in one message (e.g. a
UL-MAP message) and the UL-MAP message is added with padding bits
to match to a given number of bits in the IEEE 802.16e system. If
an M2M ranging indicator field is included in a UL-MAP IE for each
individual UE, the length of the UL-MAP message is changed, thereby
affecting decoding at the legacy UEs. To solve the problem, the
following methods may be used.
[0139] The M2M ranging indicator field may be disposed at the
padding bit area of the UL-MAP message. Thus, the padding bit area
of the conventional UL-MAP message may be reduced by the number of
bits of the inserted M2M ranging indicator field. Therefore, legacy
UEs may decode the UL-MAP message in a conventional manner, whereas
M2M devices may decode the UL-MAP message, up to the M2M ranging
indicator field.
[0140] Or a new MAP IE may be defined for M2M devices and the M2M
ranging indicator field may be included in the new MAP IE. To avoid
effects on legacy UEs, the length of the new MAP IE may be set to
be equal to that of the conventional UL-MAP IE or the new MAP IE
may be transmitted at the end of the UL-MAP message.
[0141] Or, the M2M ranging indicator field may be transmitted on a
higher-layer control signal transmission channel, not in a UL-MAP
IE. Specifically, reserved bits of a UL Channel Descriptor (UCD) or
Frame control Header (FCH) may be used.
[0142] FIG. 10 is a block diagram of an M2M device and a BS
according to an embodiment of the present invention.
[0143] Referring to FIG. 10, an M2M device 1000 and a BS 1500 may
include Radio Frequency (RF) units 1100 and 1600, processors 1200
and 1700, and memories 1300 and 1800, respectively. Each RF unit
1100 or 1600 may include a transmitter 1110 or 1610 and a receiver
1120 or 1620.
[0144] The transmitter 1110 and the receiver 1120 of the M2M device
1000 are configured so as to transmit signals to and receive
signals from the BS 1500 and another M2M device. The processor 1200
is functionally connected to the transmitter 1110 and the receiver
1120 to control signal transmission and reception to and from other
terminals through the transmitter 1110 and the receiver 1120.
[0145] The processor 1200 processes a transmission signal and then
transmits the processed signal to the transmitter 1110. The
processor 1200 also processes a signal received from the receiver
1120. When needed, the processor 1200 may store information
included in exchanged messages in the memory 1300. The M2M device
1000 having the above-described configuration may implement the
methods according to the foregoing embodiments of the present
invention.
[0146] While not shown in FIG. 10, the M2M device 1000 may include
many additional components according to its application type. If
the M2M device 1000 is designed for smart metering, it may further
include a component for power measuring. The power measuring
operation may be under the control of the processor 1200 or a
separately procured processor (not shown).
[0147] While communication is conducted between the M2M device 1000
and the BS 1500 in the illustrated case of FIG. 10, M2M
communication may also be performed between M2M devices according
to the present invention. Each terminal having the same
configuration illustrated in FIG. 10 may perform the methods
according to the foregoing embodiments of the present
invention.
[0148] Meanwhile, the transmitter 1610 and the receiver 1620 of the
BS 1500 are configured to transmit signals to and receive signals
from another BS, an M2M server, and M2M devices. The processor 1700
is functionally connected to the transmitter 1610 and the receiver
1620 to thereby control signal transmission and reception to and
from other terminals through the transmitter 1610 and the receiver
1620.
[0149] The processor 1700 processes a transmission signal and then
transmits the processed signal to the transmitter 1610. The
processor 1700 also processes a signal received from the receiver
1620. When needed, the processor 1700 may store information
included in an exchanged message in the memory 1800. The BS 1500
having the configuration may perform the methods according to the
foregoing embodiments of the present invention.
[0150] The processors 1200 and 1700 of the M2M device 1100 and the
BS 1500 command (e.g. control, adjust, and manage) operations of
the M2M device 1100 and the BS 1500, respectively. The processors
1200 and 1700 may be connected respectively to the memories 1300
and 1800 that store program codes and data.
[0151] The memories 1300 and 1800 are connected to the processors
1200 and 1700 and store an Operating System (OS), applications, and
general files.
[0152] The processors 1200 and 1700 may also be called controllers,
microcontrollers, microprocessors, or microcomputers. Meanwhile,
the processors 1200 and 1700 may be implemented by various means,
for example, hardware, firmware, software, or a combination
thereof. In a hardware configuration, the processors 1200 and 1700
may include one or more Application Specific Integrated Circuits
(ASICs), Digital Signal Processors (DSPs), Digital Signal
Processing Devices (DSDPs), Programmable Logic Devices (PLDs),
Field Programmable Gate Arrays (FPGAs), etc. which are configured
to implement the present invention.
[0153] In a firmware or software configuration, the embodiments of
the present invention may be implemented in the form of a module, a
procedure, a function, etc. Firmware or software configured to
implement the present invention may be included in the processors
1200 and 1700, or may be stored in the memories 1300 and 1800 and
executed by the processors 1200 and 1700.
MODE FOR THE INVENTION
[0154] Various embodiments have been described in the best mode for
carrying out the invention.
INDUSTRIAL APPLICABILITY
[0155] The ranging methods of an M2M device are applicable to
various wireless communication systems including 3rd Generation
Partnership Project (3GPP) Long Term Evolution-Advanced (LTE-A) and
IEEE 802.
[0156] The embodiments of the present invention described above are
combinations of elements and features of the present invention. The
elements or features may be considered selective unless otherwise
mentioned. Each element or feature may be practiced without being
combined with other elements or features. Further, an embodiment of
the present invention may be constructed by combining parts of the
elements and/or features. Operation orders described in embodiments
of the present invention may be rearranged. Some constructions of
any one embodiment may be included in another embodiment and may be
replaced with corresponding constructions of another embodiment. It
is obvious to those skilled in the art that claims that are not
explicitly cited in each other in the appended claims may be
presented in combination as an exemplary embodiment of the present
invention or included as a new claim by a subsequent amendment
after the application is filed.
[0157] Those skilled in the art will appreciate that the present
invention may be carried out in other specific ways than those set
forth herein without departing from the spirit and essential
characteristics of the present invention. The above embodiments are
therefore to be construed in all aspects as illustrative and not
restrictive. The scope of the invention should be determined by the
appended claims and their legal equivalents, not by the above
description, and all changes coming within the meaning and
equivalency range of the appended claims are intended to be
embraced therein.
* * * * *